Performance for an RF switch is generally judged based on a lowest figure of merit (FOM) achievable without degrading a drain-to-source breakdown voltage (BVDSS) of any individual transistor within a stack of transistors making up the RF switch. The FOM of a single transistor is the transistor's on-state drain-to-source resistance (RON) multiplied by the transistor's off-state capacitance (COFF). Modern silicon-on-insulator (SOI) antenna tuners include high power RF switches that are exposed to overvoltage events that occur when the antenna tuner is operating at maximum efficiency. Operating RF switches slightly above a soft breakdown voltage is not catastrophic but should be avoided to prevent accelerated degradation of the RF switch. Thus, there is a need for a need for an overvoltage detector for an RF switch.